OS 10.4 - Weird font invasion

Hi,
My Mac is being taken over by a weird fraction font. Originally it was confined to my dashboard, which I never use, but it has recently spread to my email program and some websites. I posted this in 'anything goes' a few days ago (didn't realise it was the wrong forum) and some suggested downloading Main Menu or Onyx and cleaning out my font caches. I have downloaded MainMenu and cleaned out my font caches and my system cache but it's still there. I'm worried its a virus. Any suggestions??
I'm working on a MacBook with OSX. It's about 2 years old.
Screen grabs of fonts attached.